Issue 14

D. Firrao et

alii, Frattura ed

Integrità Strutt

urale, 14 (2010)

81-92; DOI: 10

.3221/IGF-ESIS.

14.09

Ca Th the the In TN

lculation of p e calculated p charge used reflected ma particular in T are report D

ressure waves ressure valu in the exper ximum press Tab. 4, the r ed. istance [m]

induced by an es subsequen iment. For th ures, as recor esults of an e

explosion t an explosio e purpose of ded by a det xplosion exp pressure in Pa] .8 : Free air and r th distance c charge equiv n air a] E 6 9 inging on an ove through r equal to 2 se of a small general yiel e following f 2 5

n in free air calculating t ector, are mo eriment mad

depend both he intensity re important e using an e reflected pre [MPa] 14.4 7.2 ures at small d ere made, us g of TNT w P max

on the targe of pressure w and always h xplosive char

t distance an aves imping igher than th ge correspon ltiplying fact 7.2 9

d on the mas ing on an ob e free air on ding at 364

s of ject, es. g of

Calculated

Maximum

ssure

Mu

or

air [M 2 0

0.42 0.68

Table 4 harge distance pressure wi suming that a e P max i [MP >1 6 2. 1.2 0. pressures imp an object m eason a facto hat, in the ca the material ated using th (2(1+  )) resses in diff values for t lloys, 0.44 fo

eflected press

istances.

De To the

termination of relate maxim above exper

the target-to c um effective iment and as Distanc [m]

alculations w alent to 150 ffective (x9) [MPa] >144 54 19.8 11.25 8.1 object after an the bulk and has been us charge, slip o ding has not ormula which ls that may b odulus: 0.28 s alloys, 0.343 x in stainless el (  =0.31) [MPa] >109

ing multiplyin as exploded ( Effective (x7 [MPa] >115 43.2 15.84 9 6.48 a 150 g TNT c cted from fre a plausible m mation may b ed, maximum e elastic ran

g factor dat Tab. 5). .2) P max

a, obtained f

rom

0.1 0.2 0.3 0.4 0.5

Table 5 : Po ssure waves ome stronge terial. erring to the ins, thus ind losion wave  max = ( ues of maxim ab. 6, using 45 for alumin

ssible effective impinging on r. For this r hypothesis t icating that may be evalu 3(1-2  ))P max / um shear st the following ium and its a

explosion of can be refle ed to obtain r twin defor been reach is valid in th

harge at vario e surfaces, th aximum pr e manifested shear stre ge:

us distances. erefore they essure inside only in isol ss caused by

Pre bec ma Ref gra exp

can the ated an

Val in T 0.3

erent materia he Poisson m r gold and it

e hit from an and 0.31 for for copper

explosion i stainless ste and its alloys

n an aircraft el, both repo .

are also repo rted in literat

rted ure,

 max in st steel (  =

 ma

Distance [m]

ainless 0.28) a]

 max in alluminiu [MPa]

 max

 max

in [MP >3 12.

gold a]

in copper [MPa]

Effectiv

e a]

m

ste

P max

[MP

[MP >12

0.1 0.2 0.3 0.4 0.5

>250 97.2 35.6 20.2 14.6 Table 6 : Ma

9

>86 33.6 12.3 6.98 5.04

1 15

>88 34.1 12.5

50. 18. 10.4 7.5 ximum shear s or . 2, 3, and 6 which mech

1 4

42.3 15.5

5 2 2 essure waves

4.4 2.5 1.8 ngement of pr on. imate distanc a in the first

2

8.8 6.3

7.1 5.1

3 tresses arising iginating from it is then pos anical twin ev

in various me a 150 g TNT sible to deriv idence is dis

tals after impi charge explosi e the approx covered. Dat

By cha

comparing d rge from an

ata from Tab object inside

e of an explo two columns

sive 150 g T of Tab. 6 ar

NT e in

89